We are currently engaged in study of several aspects of site specific cleavage and methylation of DNA. The E. coli RI DNA restriction and modification enzymes, are being analyzed as a model system for study of sequence-specific DNA protein interaction. The interaction of the EcoRI enzymes with short DNA molecules will be investigated with the aim of obtaining thermodynamic and kinetic parameters governing the interaction. Utilizing absorbance and flourescence methods, we hope to apply rapid kinetic methods to analysis of such interactions. We have cloned the structural genes for the EcoRI enzymes and have determined their DNA sequence. Hence, we have obtained primary sequences of the two proteins. By employing site specific mutagenesis and DNA sequencing techniques we hope to establish a structure-function map for the two proteins. We are also pursuing work of the mechanism and biological function of the Escherichia coli dam methylase which is responsible for almost all 6-methyladenine residue in this organism.